Loud knocking sound in engine only 5,300kms

I’m having some issues with a used KTM RC 390 I have purchased, a knocking/tapping sound has started to occur inside the engine and I'm just hoping to get some suggestions or recommendations on how to diagnose and resolve the problem.

I have included some details below and I'm happy to provide any additional information necessary, just leave a reply or send me a message and I will respond with the requested information.
  • The noise is not there while the engine is cold, you can only hear it when the engine is warm.
  • The motorcycle only has 5300Kms on the odometer.
  • The ticking noise is in time with the engine and the speed of the knocking increases with the RPM.
  • There is no change in the noise while holding in the clutch or when it’s in gear.
  • The engine oil has no metallic flakes, shavings, pieces or sign of wear.
  • The cam chain tensioner has been replaced and adjusted with no success.
I appreciate the time you have taken to watch this video, please contact me with any help or recommendations you may have by leaving a comment or by sending a message.

 
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ReidMcT

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I'm not hearing anything particularly unusual. But maybe there is an exhaust leak? That will often sound like knocking. Easy to detect with smoke; check around the exhaust port and the pipe joint to the muffler.
 
I'm not hearing anything particularly unusual. But maybe there is an exhaust leak? That will often sound like knocking. Easy to detect with smoke; check around the exhaust port and the pipe joint to the muffler.

I checked the exhaust today as you have suggested ReidMcT and tightened the exhaust manifold bolts but unfortunately this didn't change the knocking sound in any way.

I'm planning to take it to the workshop next week and have them check the valves and piston, cylinder, cam shaft, stator etc.. for any sign of something which could cause this noise to occur before it turns into a major problem. They said I need to be prepared to replace any worn parts and it could be expensive but I plan on keeping this motorcycle long term so I'm okay with having it repaired if necessary.

Thanks for the advice and if you have any more suggestions please let me know, cheers!

 
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1JZSupra

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When you replaced the timing chain tensioner did you make sure it was extended all the way out? I know it is suppose to be "spring loaded", but I found that I needed to provide it some assistance to ensure it was properly engaging like it was suppose too.
 
When you replaced the timing chain tensioner did you make sure it was extended all the way out? I know it is suppose to be "spring loaded", but I found that I needed to provide it some assistance to ensure it was properly engaging like it was suppose too.

First I made sure it was wound all the way in then I removed the screwdriver so it sprung into the guides to apply tension. I then started the engine and with the engine running I continued to wind it out further but the knocking sound did not change.
 
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ReidMcT

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I think I would try to identify exactly where the sound is coming from. It's often easy to do with an engine stethoscope... or a long screwdriver (hold blunt end to your ear and touch the tip to various spots on the engine). It's remarkable how much detail you can discover with this method.
 
I'm not hearing anything particularly unusual. But maybe there is an exhaust leak? That will often sound like knocking. Easy to detect with smoke; check around the exhaust port and the pipe joint to the muffler.

It's difficult to captcha the sound clearly using my phone camera, perhaps I can use a screw driver as a stethoscope and place it against the microphone after finding the exactly location of where its the loudest as you have suggested. I'll do this tomorrow morning.

Here is a list of what I've done so far if anyone is interested:
  • Replaced spark plug
  • Replaced and adjusted cam chain tensioner
  • Checked exhaust for leaks and tightened any bolts (I used soapy water on the joins and checked for bubbles)
I have a repair price from the dealership for the worst case scenario where it could be piston slap, it's not going to be cheap but I doubt this is the problem.
 

1JZSupra

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I think I would try to identify exactly where the sound is coming from. It's often easy to do with an engine stethoscope... or a long screwdriver (hold blunt end to your ear and touch the tip to various spots on the engine). It's remarkable how much detail you can discover with this method.
Old school trick, I use it a lot.
 

1JZSupra

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100% sounds like it is from the timing chain still. Even in your last video you can hear it is louder on the timing chain side.
 
I’m sorry to take so long to post the results, It’s taken some time to pin point the noise with some certainty.

The noise appears to be most audible from the exhaust manifold when using the screwdriver technique mentioned by ReidMcT

I have tried some of those Liqui Molly products such as the valve cleaner and friction modifier because there’s isn’t much to lose at this stage but they don’t really appear to do anything except cost a bunch of money.

I have made an appointment with Peter Stevens (my dealership) who were kind enough to offer a pickup and drop off service for Monday or Tuesday next week.

I still have the weekend to try and resolve the issue myself if anyone has another recommendation or suggestion.
 
100% sounds like it is from the timing chain still. Even in your last video you can hear it is louder on the timing chain side.


If it’s something related to the timing chain that would be great, far better than having to replace a piston and cylinder.
 
Thanks everyone for the advice, it was indeed the dreaded piston slap and I had to replace both the piston and cylinder. I'm fairly certain the seller was fully aware of this problem.
 

acruhl

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I missed this. I would have guessed a bearing but piston slap is pretty common. The bottom line here is you know how your bike sounded at one time and if it changes you need to figure out why. A friend of mine had a big end bearing go on his Ducati with 9000 miles on it. It happens. The real question is if it's common (in Ducatis, no) and how you get treated if you are still within warranty, or even if you're not sometimes. Pistons really shouldn't go that soon given that service has been done. Which is the problem, kids these days think that bikes are for holding against the rev limiter and will last forever (forever being their attention span) so they don't do service. I generally don't buy used sport bikes.
 
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